Subwavelength nanostructures integrated with polymer‐packaged iii–v solar cells for omnidirectional, broad‐spectrum improvement of photovoltaic performance

Abstract

Reduction in surface and interface reflectance via the integration of subwavelength nanostructures in flexible polymer packaging material combined with incorporation of dielectric nanoislands into a conventional two-layer antireflection coating has been demonstrated, analyzed and optimized. Transmittance measurements of moth-eye textured polymer packaging sheets with different tapered pillar heights fabricated by reactive-ion etching and nanosphere lithography provide insights into the choice of the optimum nanostructure dimensions. Detailed computational modeling and simulations elucidate the physical nature of the antireflection performance of dielectric nanoisland structures integrated with a commercial two-layer antireflection coating, and provide guidance for design of the nanoisland structure for optimum antireflection performance. Measurements show that the integration of appropriately designed nanostructures in both polymer packaging material and conventional antireflection layers enables substantial increases in external quantum efficiency (E.Q.E.) and short-circuit current density (J sc ) over a broad range of incident angles, compared to structures with conventional bilayer antireflection coatings and unpatterned polymer packaging sheets. A 1.1× increase in J sc , derived directly from E.Q.E. measurements, at normal incidence, increasing to 1.67× improvement at 80°angle of incidence, suggests that such an approach is promising for a variety of photovoltaic applications, particularly those where solar tracking is not feasible or practical.

Light-trapping optimization in wet-etched silicon photonic crystal solar cells

“…In order to improve the cell efficiency, anti-reflective surface texturing 17 is applied to crystalline silicon solar cells to reduce light reflection [18][19][20] at the wafer surface. If the lattice constant of surface texturing is large compared to the wavelengths of incident photons, the texture will induce light reflection between the surfaces of the texture, resulting in solar ray-trapping [21][22][23][24][25][26] and reduced light reflection.…”

Structural coloration with hourglass-shaped vertical silicon nanopillar arrays

“…In addition to the resonance effect, the structural coloration is also aided by the subwavelength tapering of the body of the pillar, which enables index grading between the low index medium and the high index substrate. This suppresses broadband Fresnel reflections at the substrate/air interface, similar to moth-eye antireflection structures [49][50][51].…”

Integrated broadband bowtie antenna on transparent substrate

“…The bowtie antenna has compact size smaller than 1cm 2 . This bowtie antenna has potential applications in photonic detection of free-space electromagnetic waves [29][30][31], RF photonic links and devices [32] complex electromagnetic structures [33], ground penetrating radar [5], THz wave detection [34], plasmonic sensing [35], nano-antenna arrays [8], quantum emitter [36], optical antennas [37], and even light trapping for photovoltaics [38][39][40]. In addition, from fabrication point of view, solid bowtie antennas [41] or contour bowtie antennas [7] can be fabricated by inkjet printing techniques, which is compatible with roll-to-roll manufacturing processes [42].…”